Outlook Web Access (OWA), enabled with Exchange servers and newer browsers, has increased its capabilities as the technology has advanced, making the experience for your remote or mobile workers more effective and productive. The upgrade in capability from earlier versions of Exchange to Exchange 2003, just in the presentation of the data and in search capabilities, is impressive.
The trouble is that every time programmers add more capability, OWA uses more bandwidth. The demand for more features means that the bandwidth gets used up faster than the rate at which hardware engineers can create it.
At some point, your users will find that their OWA experience is slowing down, and the availability of advanced features buys them little if the delivery of those features becomes painfully slow. In the case of users with dial-up access to OWA, the problem could grow quickly.
How can you improve performance? One way is to use the Reach Version of OWA instead of the Rich Version.
Reach is a sort of stripped-down version of the OWA capability. The main difference between the two versions is the user interface and breadth of features.
When a browser requests access to the Exchange server, that server determines what version browser the request is coming from, and responds with the appropriate version of OWA. If users are running Exchange 5.0 or later, then they get the Rich Version, which supports XML and DHTML. Not many people are likely using Internet Explorer 5.0 at this point, but if they are, then they'll get the Reach Version, which has a simpler user interface and lacks features like new mail notification, search and drag-and-drop editing. If your users are equipped with an older version of Internet Explorer, or are using a non-Microsoft browser that doesn't support these newer protocols and you want to use the reach client, just leave things as they are, and you'll get it.
But what if you don't want to use an older version of the browser? Or, what if you do decide to opt for the reach client, and then find that some users need more capability? It seems that users always want more, and it won't be surprising if that is the case with the reach client of OWA.
Not to worry. You don't have to use an older version of the browser, and you can solve the different capability dilemma by segmenting your Outlook Web Access so that some clients get a richer experience than others, all with the newer versions of Internet Explorer. Someone who needs to be able to conduct searches, for example, would be able to do that, while the majority, who don't have that need, couldn't.
Conversely, if you want to force some people to use the Reach Version, even though they are using Internet Explorer 5.0 or greater, you can do that.
The capability is called segmentation, and has been available since the release of Exchange 2000 Server Pack 2. It allows you to segment on a per-client or a per-server basis, or both, to deliver the kind of experience that your users need, while still maximizing the bandwidth capacity of your Internet links.
There are a couple ways that you can segment if you want to give the reach client experience to the users of browsers from version 5.0 on: either hard code the server to send all clients the reach client experience, or you can write an ISAPI filter to rewrite the user header on incoming requests. A Microsoft knowledge-base article shows how to handle this approach.
David Gabel has been testing and writing about computers for more than 25 years.
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